Get quotes for custom CNC machined parts
Tight-tolerance milled and turned parts in metal and plastic, made to your specifications. Upload your CAD files or drawings and we'll source competitive quotes from qualified manufacturing partners.
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How OpenSpindle works
We tap our partner network. You get the best-match quote.
Upload your part and we tap our network of partner shops to get you a competitive, all-in quote that is the best match for the job.
One upload
A CAD file or a sketch. That is the whole ask on your end.
Your best-match quote
Sourced from the partner shops set up for your exact part.
All-in, on your timeline
Machining, finishing, and shipping detailed to your turnaround.
Materials our machining shops run
CNC machining starts from solid billet. If your alloy is not here, ask when you request a quote.
Specs
Tolerances you can expect
| Feature | With a drawing | No drawing supplied |
|---|---|---|
| Linear dimension | ±0.005 in | ISO 2768 Medium |
| Hole diameter (not reamed) | ±0.005 in | ISO 2768 Medium |
| Shaft diameter | ±0.002 in | ISO 2768 Medium |
| Surface finish | 125 Ra as-machined | 125 Ra as-machined |
Shops quote to your drawing. Tighter tolerances are available from shops running CMM inspection. Ranges are typical, not guaranteed until a shop quotes your specific part.
Design rules
How to design for CNC Machining
The design choices that most affect whether a machined part is easy and cheap to make.
| Design rule | Typical spec | Why |
|---|---|---|
| Min internal corner radius | >= 1/3 x pocket depth | An end mill cannot cut a sharp internal corner; a radius lets the tool reach it. |
| Min wall thickness | 0.030 in metal / 0.060 in plastic | Thinner walls chatter against the cutter and need a slow finishing pass. |
| Max pocket depth | <= 4x tool diameter | Deeper pockets need a longer tool and slower feeds, which adds cost. |
| Min hole diameter | >= 0.040 in (1 mm) | Smaller holes need specialty micro-drills that break easily. |
| Tapped thread depth | 1.5 to 2x thread diameter | Threads past ~2x diameter add cost without adding strength. |
| Standard tolerance | +/- 0.005 in | Tighter is available from shops running CMM inspection; call it out only where it functions. |
These are typical starting points. A shop confirms feasibility against your specific drawing and material.
Reference
Related reference charts
Free spec + tolerance charts for designing these parts.
Secondary operations
Inserts, hardware and finishing
Threads and inserts
Tapped holes, heat-set inserts, press-fit and PEM-style hardware installed before the part ships. Note the callouts on your drawing.
Finishing
Applied after machining, so each one adds days. As-machined ships fastest; anodize, powder coat, and passivation are common on machined parts.
| Finish | Materials | Adds | Can be applied with |
|---|---|---|---|
| As-machined | All | +0 days | Anything |
| Bead blast | Aluminum, stainless | +1-2 days | Anodize, passivation |
| Powder coat | Aluminum, steel | +3-5 days | Bead blast. Not with anodize. |
| Passivation | Stainless only | +2 days | Bead blast |
Worth knowing: powder coat adds 0.002 to 0.005 in per side. On tight clearances or small holes, account for it or mask them.
Process comparison
CNC machining vs other processes
When another process is a better fit than milling or turning a part from solid stock.
| Process | Best for | Typical volume | Choose it over CNC Machining when |
|---|---|---|---|
| CNC Turning | Round parts: shafts, pins, bushings, fittings | Prototype to production | The part is cylindrical and made on a lathe rather than a mill. |
| Sheet Metal | Brackets, panels, enclosures | Prototype to production | The part can be made from bent flat sheet, which is far cheaper than cutting from solid. |
| 3D Printing | Complex geometry, fast prototypes | One-off to low volume | Geometry is too complex to machine, or you need a part in hand in a day. |
| Injection Molding | High-volume identical plastic parts | 1,000+ | You are making thousands of the same plastic part and can amortize a mold. |
Get a better quote
Getting a quote that comes back fast
| Instead of | Send this |
|---|---|
| "CNC part, need a quote" | "6061-T6 bracket, tolerances per drawing, qty 50, as-machined" |
| "Aluminum, tight tolerance" | "6061-T6, ±0.005 in on the two bore centers only" |
| "ASAP" | "Need in hand by the 30th, happy to pay for rush" |
Tolerance drives cost more than any other line on your drawing. Call out only the features that actually need it.
Applications
Industries we serve
Machine shops on OpenSpindle make parts for regulated and demanding industries, including shops with AS9100 and ITAR registration.
More on OpenSpindle
Need a different process?
Get a quote for these capabilities too.
Designing for this process
What actually changes your quote
Not a definition of CNC machining. The design choices that move your price and lead time.
Internal corners have a radius
An end mill cannot cut a sharp internal corner. Design a radius of at least one third the pocket depth, or the shop adds an operation.
Deep pockets cost more than wide ones
Past about four times the tool diameter the shop steps down to a longer tool and slower feeds. Shallow and wide is cheaper.
Every tolerance callout is money
±0.001 in on a face that does not mate adds inspection time for nothing. Tolerance only the features that function.
Thin walls chatter
Under 0.030 in in metal, walls flex against the cutter. Expect a finish pass, or thicken the wall.
Questions
Frequently asked questions
Plus or minus 0.005 in is standard with a drawing, and shops running CMM inspection hold tighter on critical features. Send your drawing when you request a quote and the shop confirms feasibility before cutting.
Get CNC machining quotes
Upload your drawing and we'll source competitive quotes from qualified manufacturing partners.
STEP · STL · IGES · DWG · DXF · PDF · and more
Uploads are secure & confidential